Fastener feed mechanism

ABSTRACT

A feed mechanism for use in headed fastener driving apparatus wherein mated screw threads are provided on a turret member and feed screw to rotate said turret member and move a headed fastener from a magazine into a driving passage. Said feed mechanism is further characterized by the use of a pawl to limit the rotation of said feed screw and wherein said pawl is resiliently attached to said driving apparatus by the use of a shock absorbing element.

United States Patent Inventors Appl. No.

Filed Patented Assignee FASTENER FEED MECHANISM Primary Examiner-Granville Y. Custer, Jr. Anorney-Cushman, Darby & Cushman ABSTRACT: A feed mechanism for use in headed fastener 5 Claims, 6 Drawing Figs. driving apparatus wherein mated screw threads are provided Us Cl 227,136 on a turret member and feed screw to rotate said turret h" .ci nzsc 00 member and move a headed fastener from a magazine into a mi 227 36 driving passage. Said feed mechanism is further characterized by the use of a pawl to limit the rotation of said feed screw and wherein said pawl is resiliently attached to said driving apparatus by the use of a shock absorbing element.

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1 4, A 32 6W7 ATTORZISKB PATENTED BEBE! B11 SHEET 3 BF 3 FASTENER FEED MECHANISM BACKGROUND OF THE INVENTION The present invention relates generally to improvements in fastener driving apparatus, and more particularly to an apparatus for driving fasteners from a magazine into a workpiece wherein a new and improved feeding mechanism is used.

Magazine-fed fastener driving apparatus are well known in the prior art, as, for example, see the U.S. Pat. Nos. to Maynard 3,259,292, July 5, 1966 and Colechia 3,330,462, July ll, 1967. These power driven fastener driving apparatus have many advantages both from a labor saving standpoint and a time saving standpoint which make them desirable to use in the construction industry for driving heavy duty headed fasteners. Because these apparatus are used in driving heavy duty headed fasteners, they must be durable to endure the forces developed in driving a fastener in a single stroke and feeding the fasteners by use of a trip lever.

The fastener feeding means for these apparatus are actuated by use of a movable trip lever mounted on the lower portion of the apparatus so that the trip lever is moved by placing it in contact with a workpiece and pressing down on the upper end of the apparatus. A feed screw is moved by the trip lever and rotates a turret within the apparatus to move successive fasteners into a driving position. The feed mechanism operates to rotate the turret until the fastener is in the feed position, where further rotation of the turret is prevented by a stop means. This stopping of the rotation of the turret subjects the feed screw to torsional stresses which in the past have produced failures in the screw itself.

The general purpose of this invention is to provide a new and improved feed mechanism which adequately functions to feed fasteners in to a driving position and is stronger and more durable and less likely to fail due to the repeated stressing created in the feed and drive processes.

An object of this invention is to provide a feed screw member in the feed mechanism which directly converts the translational motion of the trip lever into rotational motion of the turret member without additional mechanisms mounted between the feed screw and the turret member. This is accomplished by providing a screw thread engagement directly between the screw and the turret member. The lack of additional elements provides the obvious advantage of allowing the feed screw to be made larger and stronger for a given turret size. This additional screw size and strength becomes important when considering the forces to which this screw is sub jected during operation of the apparatus.

Still another object of the present invention is the provision of a shock absorbing element in the feed mechanism to further reduce the effect of the forces produced during operation of the apparatus and prevent failure in the feed screw.

A still further object is to produce a feed mechanism which continues to operate when used in the presence of dirt or other fouling matter.

An even further object is to produce a feed mechanism which can be easily cleaned and serviced.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will hereinafter become fully apparent from the following description of the annexed drawings wherein;

FIG. 1 is a perspective view of the fastener driving apparatus applying the principles of the present invention illustrating the general arrangement of the component parts of the apparatus;

FIG. 2 is an enlarged fragmentary sectional view taken along line 2--2 of FIG. I showing the turret member and delivery passage,

FIG. 3 is an enlarged fragmentary sectional view taken along line 3--3 of FIG. 2 showing the trip lever and feed screw in the extended position;

FIG. 4 is an enlarged fragmentary sectional view of the rachet portion of the feed apparatus taken along lines 4-4 of FIG.3;

FIG. 5 is an enlarged fragmentary sectional view illustrating the resilient bushing arrangement of the present feed apparatus taken along lines 5-5 of FIG. 3;

FIG. 6 is an enlarged fragmentary sectional view similar to FIG. 3 showing the trip lever and feed screw in the upper position adjacent the body of the apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1, a fastening driving apparatus generally indicated at 10, embodying the principles of the present invention. The apparatus 10 includes an elongated housing section 12 having a handle 14 extending laterally outward from the central portion thereof and a fastener handling section, generally indicated at 16, fixedly secured to one end of the housing section 12 and extending outwardly therefrom in alignment with handle 14 and in close space relationship thereto.

The elongated section 12 houses a pneumatically actuated fastener driving mechanism of a suitable construction, an embodiment of which is disclosed in the U.S. Pat. to George A. Maynard No. 3,259,292 of July 5, 1966, the disclosure of which is hereby incorporated by reference in this specification.

The present invention is more particularly concerned with an improvement in the feed mechanism 24 of the fastener handling section 16 disclosed in the above-mentioned Maynard patent.

The details of construction and the relationship between the fastener handling section 16 and housing section 12, and handle 14 are disclosed in the above patent and the details of construction of the pneumatic actuated fastener driving mechanism and detail mode of operation thereof form no part of the present invention.

For the present purposes, it is sufficient to note that the mechanism includes a fastener driving element 18, see FIG. 3, mounted within the body section 12 for reciprocating movement between a fastener receiving position disposed within the housing section 12 and a fastener driven position extending outwardly therefrom. The fastener driver element 18 serves to drive the leading fastener of the fastener package, into the workpiece during its movement from the fastener receiving position to its fastener driven position.

A fastener package (not shown) is constructed in accordance with the disclosure of the U.S. Pat. to Peterson No. 3,083,369 of Apr. 2, 1963, and includes a multiplicity of common nails 19, each having a shank terminating at one end at a point and the other end in an enlarged circular head. The nails 19 of the package are connected in parallel relation by a pair of parallel flexible flangable wires 21 welded to the shank of each nail.

The fastener handling section 16 includes a magazine structure 20 for receiving and supporting the fastener package in conical parallel formation, a guide structure 22 for receiving and guiding the leading portion of the outer coil layer of the fastener package supported within the magazine section 20, into a feed mechanism 24. This feed mechanism 24 engages the leading portion of the fastener package within the guide section 25 and effects movement of the leading fastener 28 into a fastener delivery passage 26.

A pneumatically actuated driving mechanism is operable to effect movement of a driver element 18 from its fastener receiving position when the leading fastener 28 has moved into fastener delivery passage 26 and the operator has pressed the finger trigger 30 mounted adjacent handle 14, and the apparatus has been moved into engagement with the work to depress a trip lever 32 movably carried by the fastener handling section 16. During the movement of the driver rod from its fastener receiver position to its fastener delivery position, the leading fastener 38 within the fastener delivery passage 26 is moved outward therefrom by the driver element 18 into the workpiece, the precise manner in which the movement is accomplished may be determined by referring to the aforesaid Maynard patent. As disclosed therein, the pneumatically actuated driving mechanism is such as to recycle the driver element 18 back into the fastener receiving position for a repeated movement of this cycle in the above-mentioned starting position.

Referring now more particularly to FIGS. 2 and 3, a guide section 25 is shown as having an elongated slot 23 into which the nails 19 longitudinally fit. The exact structure and detail of this delivery passage is disclosed in the aforementioned patent to Colechia et al. Suffice to say that the guide structure 22 and slot 23 form a passageway for the fasteners traveling from the magazine structure to the feed mechanism 24.

As best shown in FIGS. 3 and 6, a rigid nosepiece 42 includes a generally cylindrical shaped work engaged nose portion 44 having a fastener receiving bore 46 formed therein aligned within the delivery passage 26 is shown as attached to the fastener handling section 16 by suitable bolts 47, so that the nosepiece can be easily removed.

The trip lever 32 shown in FIG. 3 in its extended position is mounted on the nosepiece 42 for pivotable movement about an axis transverse to the axis of the bore 46. This trip lever 32 is mounted to rotate about a pivot pin 50 which is mounted on an outstanding portion of the nosepiece 42 and located away from the bore 46.

A flange .53 is also formed on the trip lever 32 to limit the rotation of the trip lever 32 in a direction away from the tool by engaging a portion of the nosepiece 42. A pawl 52 is also mounted on the trip lever 32, and its construction and operation will be herein later described. The trip lever 32 is also provided with resilient bushings 54 which contact the pin 50, to absorb shock generated in or transmitted to the trip lever 32.

In the present embodiment the pawl 52 is disclosed as being mounted on the trip lever but the pawl could be mounted on a nonmoving portion of the apparatus such as the nosepiece. If the pawl were mounted on a nonmoving portion of the apparatus, it would be desirable to provide a resilient mounting which would absorb the shock transmitted to the pawl itself.

Referring now to FIGS. 2, 3 and 6, a detail of the feed mechanism 24 can be seen as comprising a turret member 34 mounted for rotation in a cylindrical space 35 formed at the end of the elongated guide slot 23. The turret member 34 is formed with a plurality of circumferentially spaced fasteners receiving pockets, 36, each pocket 36 being defined by an elongated surface of arcuate configuration in cross section, the curvature of the arc being of a size to receive a nail head therein. Although, in the present embodiment of this invention the turret is shown with six fastener receiving pockets 36 mounted thereon, it is anticipated that a different number of pockets could be used if other portions of the feed mechanism were appropriately adjusted to conform with these changes.

Each of the fluted portions of the turret member 34 forming the pocket 36, is provided with a pair of longitudinally spaced notches 38. Each notch 38 is defined by an inclined upper guide surface 39 and a lower transversely extended surface providing a cutting edge 40. As shown in FIG. 3, these notches are positioned within the turret member to receive and guide the frangible wires 21 of the fastener package.

The turret member 34 is provided with a central bore 62 extending axially, therethrough. This bore 62 is of a size at either end of the turret to allow the insertion of a bushing to permit rotation of the turret. An upper bushing 56 is rotatably fitted into the upper end of the bore 62 and has a cylindrical portion 60 on its upper end which is inserted into a corresponding mounting surface on the housing 12. The lower end of the bushing 56 is also provided with a cylindrical spring guide 64 which is centrally located in the bore 62 and whose function will be later described.

A lower bushing 58 is rotatably fitted into the lower end of the bore 62 and provides the bearing between the turret 34 and the nosepiece 42. This bushing 58 is provided with a central bore 68 whose function will be subsequently described.

The turret member .34 also has an internally threaded portion 70 which is coaxial with the axis of rotation of the turret and located in the bore 62. The purpose of this threaded portion 70 will be later described. Mounted in the upper end of the central bore 62 between the threaded portion 70 and the upper bushing 56 is a helical coil spring 72. As described earlier, the upper bushing 56 has a cylindrical spring guide 64 which fits into the center of the spring 72 and positions the upper end of the spring. Mounted on the lower end of the spring to slide in the upper end of the bore 62 is a spring button 74. This button 74 has a cylindrical portion 75 which is insorted into the lower end of the spring 72. The other end of this button has a centrally located countersunk bore 84. The countersunk portion of this hole forms a conical surface the function of which will be later described. In this configuration, the button 74 is free to slide axially along the upper end of the bore 62 so that the spring 72 resiliently forces the button 74 in a downward direction toward the threaded portion 70.

An elongated feed screw 76 is mounted within the bore 62 of the turret member 34 with its upper end having externally threaded portion 78 and its lower end having a rachet portion 80. This screw is of such a size as to axially slide through the central bore 68 of the lower bushing 58.

The threaded portion 78 is of such a size that it will mate with the internally threaded portion 70 of the turret member 34. These threads on the feed screw 76 and turret member 34 are such that when the feed screw is prevented from rotating in an antifeed direction and moved axially into the turret member; that the turret member will be forced to rotate in a feed direction (see FIG. 6). The upper end of the screw 76 is provided with a conical shaped bearing surface 82 which contacts with the corresponding surface in bole 84 on the spring button 74. This contact allows the screw to contact the spring button and have relative rotation with respect thereto.

The lower end of this screw end 76 is provided with an areaate bearing surface 86 which contacts the trip lever 32 so that the feed screw 76 is axially moved in the bore 62 of the turret member 34 by the movement of the trip lever 32 but allowed to rotate relative thereto. A pawl 52 is mounted to contact the rachet portion of the feed screw and to prevent rotation of the feed screw in the antifeed direction but to allow rotation of the feed screw in the feed direction. This rachet portion 80 is formed with 7 separate rachet teeth 81 which extend radially from the lower portion of the screw 76 and contact the pawl 52. It should be pointed out however that the frictional contact between the pawl 52 and the rachet portion 80 produces a resistance to rotation of the feed screw in feed direction but compared to the resistance to rotation created by the rachet tooth, pawl engagement encountered in the antifeed direction, the resistance in the feed direction is relatively small.

OPERATION OF THE DEVICE Before commencing operation, it is first necessary to place a fastener package into the fastener magazine structure 20 and to feed the fastener package through the guide section 25 in the feed mechanism 24 so that the leading fastener 28 is engaged by the turret member 34. As the fastener driving apparatus is placed adjacent a work surface, the trip lever 32 contacts the work surface and is forced to move relatively toward the nosepiece and rotates with respect to the pivot pin 50 to the position shown in FIG. 6. This forces the feed screw 76 to move in an upward and inward direction with respect to the turret member 34. The pawl 52 prevents the feed screw from rotating in an anticlockwise direction and the threaded portions 70 and 78 force the turret member to rotate in a feed direction and move the leading fastener to the delivery passage 26.

By using a direct screw thread engagement between the feed screw and the turret member, the size and strength of the feed screw can be increased thus making a stronger and more durable feed mechanism.

lOlOlS 0l38 It can also be seen that by locating the ratchet outside of the turret member there is more space available for the rachet and that a stronger pawl can be used. The pawl rachet arrangement has advantages in its increased strength over other arrangements and its relatively simple structure insures less likelihood of failure of malfunction. There is also the added advantage that the rachet located on the trip lever can be easily cleaned and therefore, can be kept in proper working order.

Means are provided (see the patent to Maynard et al.) to sense the position of the leading fastener and to prevent further rotation of the turret member 34, trip lever 32, and feed screw 76 when the leading fastener is in the proper position in the delivery passage 26. It can be seen that this limiting of the movement of the turret member 34, trip lever 32, and feed screw 76 creates impact forces in the feed mechanism. One of these forces is created by the torque in feed screw 76 which is transmitted to the trip lever 32 by the pawl 52, and from the trip lever 32, to the resilient bushings 54. It is the function of this bushing 54 to act as a shock absorber to absorb as much of this torque and the other impact forces as possible. By absorbing these forces, the elements of the feed mechanism are protected from damage and failure therefrom.

Once the fastener is in the proper position, the fastener driver element 18 can be activated to drive the fastener from the delivery passage into the workpiece. As the tool is moved away from the workpiece, the trip lever 32 is allowed to rotate away from the nosepiece 42 (to the position shown in FIG. 3) until flange 53 contacts the nosepiece.

It is important here to note that the rachet portion of the feed screw has seven teeth while there are only six fastener receiving pockets in the turret member. This configuration of having more rachet teeth than receiving pockets ensures that the feed screw on its return stroke will rotate in a feed direction an angle greater than the angle between adjacent rachet teeth. This configuration insures that the feed screw will always advance the turret on the succeeding feed stroke sufficient rotation to deliver the next leading fastener to the delivery passage.

it also should be pointed out that the relative resistance to rotation of turret member in the antifeed direction is greater than the resistance to rotation of the feed screw in the feed direction. This is due to the fact that the turret member is larger thus having a larger inertia and the bushings used in the turret create more friction drag on the turret that the pawl creates on the feed screw. In addition to this, the interconnected fasteners contact the turret member and tend to resist its rotation. Due to this relative resistance to rotation of the feed screw and the turret member, the force of the spring 72 on the spring button forces the feed screw to move in a downward direction with respect to the turret member while the pawl allows the screw to rotate in a feed direction.

After the trip lever has returned to the position illustrated in FIG. 3, the apparatus is ready to feed another fastener into the delivery passage 26 and repeat the process.

Thus it can be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiment has been shown and described only for the purpose of illustrating the principles of this invention and is subject to extensive change without departing from said principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

We claim:

1. In combination with an apparatus for driving fasteners into a workpiece or the like having, a body structure with a fastener delivery passage arranged to receive a fastener for transverse inward movement therein and for longitudinal outward movement therefrom,

a magazine structure carried by said body adapted to receive a fastener package including a multiplicity of parallel headed fasteners interconnected in series,

driving means carried by said body structures for movement between a fastener receiving position and a fastener driving position so that the leading fastener of said package can be moved transversely into said delivery passage when in said fastener receiving position for movement longitudinally out of said delivery passage by said driving means during the movement of the latter from said fastener receiving position to said fastener driven position,

guide and feed means between said magazine and said fastener delivery passage for guiding the leading portion of the fastener package extending from said magazine to said fastener delivery passage,

said guide and feed means comprising, a turret feed member having a central axis of rotation disposed parallel with the longitudinal extent of said fastener delivery passage and a plurality of circumferentially spaced longitudinally extending fastener receiving pockets of a size throughout the longitudinal extent thereof to receive a portion of the periphery of a fastener head therein,

said turret member being mounted on said body structure for successive incremental movements about the axis of rotation thereof in a feed direction to bring successive peripheral pockets thereof into an operative position in cooperating communicating relation to said fastener delivery passage so that said leading fastener is received within the pocket in operative position and is disposed in alignment within said delivery passage for longitudinal movement therefrom by said driving means,

an elongated feed screw mounted for longitudinal movement with respect to said turret member between first and second positions,

contact trip means operatively associated with said feed screw for effecting movement of said feed screw from said first position in one direction towards said second position when said apparatus is moved into operative relationship with a workpiece,

spring means operatively connected with said feed screw for effecting movement of the latter in the opposite direction into said first position when said apparatus is moved out of operative relationship to the workpiece,

and motion transmitting means for effecting an incremental movement of said turret member about the axis of rotation thereof in said feed direction to bring a peripheral pocket thereof into operative position in cooperating communicating relation to said fastener delivery passage in response to the movement of said feed screw from said first position towards said second position, the improvement which comprises:

said motion transmitting means comprising interengaging internal and external thread means on said turret member and said feed screw respectively,

said feed screw including an end portion extending outwardly of said turret member having a series of rachet teeth formed thereon of a number exceeding the number of said pockets,

pawl means mounted for operative engagement with a rachet tooth for limiting rotational movement of said feed screw during the longitudinal rotational movement thereof in said one direction so that said thread means will effect said incremental rotation of said turret member in said feed direction and for permitting rotational movement of said feed screw during its longitudinal movement in the opposite direction so that said thread means will not effect rotation of said turret member in said antifeed direction,

and means operatively connected between said pawl means and said body for absorbing energy transmitted to said pawl means by the engagement of a rachet tooth therewith.

2. An apparatus as described in claim 1 wherein said contact trip means is rotatably mounted on said body to rotate about an axis which is transverse to the axis of rotation of said turret member.

3. An apparatus as described in claim 2 wherein said pawl means is carried by said trip means.

4. An apparatus as described in claim 3 wherein said energy absorbing means comprise resilient bushings mounted on the pivot of said turret member.

5. An apparatus as claimed in claim 3 wherein said pawl is a flat piece of spring material mounted on said trip means with one end resiliently urged against said rachet teeth.

* v i i 

1. In combination with an apparatus for driving fasteners into a workpiece or the like having, a body structure with a fastener delivery passage arranged to receive a fastener for transverse inward movement therein and for longitudinal outward movement therefrom, a magazine structure carried by said body adapted to receive a fastener package including a multiplicity of parallel headed fasteners interconnected in series, driving means carried by said body structures for movement between a fastener receiving position and a fastener driving position so that the leading fastener of said package can be moved transversely into said delivery passage when in said fastener receiving position for movement longitudinally out of said delivery passage by said driving means during the movement of the latter from said fastener receiving position to said fastener driven position, guide and feed means between said magazine and said fastener delivery passage for guiding the leading portion of the fastener package extending from said magazine to said fastener delivery passage, said guide and feed means comprising, a turret feed member having a central axis of rotation disposed parallel with the longitudinal extent of said fastener delivery passage and a plurality of circumferentially spaced longitudinally extending fastener receiving pockets of a size throughout the longitudinal extent thereof to receive a portion of the periphery of a fastener head therein, said turret member being mounted on said body structure for successive incremental movements about the axis of rotation thereof in a feed direction to bring successive peripheral pockets thereof into an operative position in cooperating communicating relation to said fastener delivery passage so that said leading fastener is received within the pocket in operative position and is disposed in alignment within said delivery passage for longitudinal movement therefrom by said driving means, an elongated feed screw mounted for longitudinal movement with respect to said turret member between first and second positions, contact trip means operatively associated with said feed screw for effecting movement of said feed screw from said first position in one direction towards said second position when said apparatus is moved into operative relationship with a workpiece, spring means operatively connected with said feed screw for effecting movement of the latter in the opposite direction into said first position when said apparatus is moved out of operative relationship to the workpiece, and motion transmitting means for effecting an incremental movement of said turret member about the axis of rotation thereof in said feed direction to bring a peripheral pocket thereof into operative position in cooperating communicating relation to said fastener delivery passage in response to the movement of said feed screw from said first position towards said second position, the improvement which comprises: said motion transmitting means comprising interengaging internal and external thread means on said turret member and said feed screw respectively, said feed screw including an end portion extending outwardly of said turret member having a series of rachet teeth formed thereon of a number exceeding the number of said pockets, pawl means mounted for operative engagement with a rachet tooth for limiting rotational movement of said feed screw during the longitudinal rotational movement thereof in said one direction so that said thread means will effect said incremental rotation of said turret member in said feed direction and for permitting rotational movement of said feed screw during its longitudinal movement in the opposite direction so that said thread means will not effect rotation of said turret member in said antifeed direction, and means operatively connected between said pawl means and said body for absorbing energy transmitted to said pawl means by the engagement of a rachet tooth therewith.
 2. An apparatus as described in claim 1 wherein said contact trip means is rotatably mounted on said body to rotate about an axis which is transverse to the axis of rotation of said turret member.
 3. An apparatus as described in claim 2 wherein said pawl means is carried by said trip means.
 4. An apparatus as described in claim 3 wherein said energy absorbing means comprise resilient bushings mounted on the pivot of said turret member.
 5. An apparatus as claimed in claim 3 wherein said pawl is a flat piece of spring material mounted on said trip means with one end resiliently urged against said rachet teeth. 